A variety of techniques are available for denaturing proteins. Physical methods such as heat, sound waves, UV light, and ionizing radiation, freezing and mechanical shearing forces are commonly used. Organic solvents and solutes (acids, base, acetone, alcohol, urea, guanidine salts, amides, salicylates ionic detergents inorganic electrolytes and proteolytic enzymes are commonly used to precipitate proteins.
Blood serum or plasma is generally treated with organic solvents such as ethanol, ethanol-petroleum ether, dioxane, dimethylsulfoxide, dimethylformamide or acetone or mixtures thereof to precipitate proteins. However, in order to obtain a clear supernatant a mechanical phase spearation such as centrifugation or filtration is required.
Unexpectedly, it has been found that treating a volume of blood serum or plasma with about 1.4 or more volumes of acetonitrile, propionitrile, tetrahydrofuran or mixtures thereof rapidly precipitates serum or plasma protein and provides a clear supernatant which does not require mechanical phase separation and is suitable for analysis by conventional techniques.